Focus adjustment apparatus and control method therefor

ABSTRACT

A focus adjustment apparatus that displays an in-focus state in a display region in association with control of a focus lens position. The apparatus includes a signal generation unit configured to output a pair of image signals from a focus detection region having a plurality of corresponding display regions, the image signals being generated by photoelectrically converting light having passed through an imaging optical system, and a control unit configured to detect a phase difference of the pair of image signals output from the focus detection region, and to control a position of the focus lens based on the phase difference detection result. The control unit detects the phase difference corresponding to divided regions formed by dividing the focus detection region, and displays an in-focus state in the display region in accordance with the control of the focus lens position control based on the phase difference detection result.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a focus adjustment apparatus used forimage capturing apparatuses, such as still cameras, video cameras, orvarious observation apparatuses.

2. Description of the Related Art

Conventionally, for performing automatic focus (AF) in a camera, a focusdetection apparatus with a so-called phase difference detection methodis known. In the phase difference detection method, a light flux from anobject, having passed through different exit pupil regions of aphotographic lens, is caused to form an optical image on each of a pairof line sensors, and photoelectrically converted into a pair of objectimages. Thereafter, based on the object images, an amount ofdisplacement between relative positions of the pair of object images iscalculated (hereinafter, referred to as phase difference calculation).To perform autofocus, the photographic lens is driven based on thedefocus amount obtained by the phase difference calculation. In thefocus detection apparatus of this type, line sensors are arranged atpositions corresponding to each of a plurality of AF frames (focuspoints). An example of this technique is discussed in Japanese PatentApplication Laid-Open No. 2011-232544.

In recent years, for the purpose of an enhancement of AF performance,the number of AF frames has been increased. When the number of AF framesis increased, owing to restriction of an optical layout, a plurality ofAF frames may be arranged in high density with respect to a pair of linesensors. In this case, a plurality of AF frames corresponding to theline sensors with which the focus control has been performed will bedisplayed. However, the focusing result for an object is obtained inwhich an AF frame, among the plurality of AF frames, cannot be displayedto inform the user of the AF state. As a result, whether optimum focusis achieved on a user's intended target may not be known by display.

SUMMARY OF THE INVENTION

At least one embodiment of the present invention is directed to a focusadjustment apparatus capable of allowing a user to visually recognize afocused object more reliably in a camera that performs AF with amultipoint AF system.

According to an aspect of the present invention, a focus adjustmentapparatus configured to display an in-focus state in a display region inaccordance with control of a focus lens position, includes a signalgeneration unit configured to output a pair of image signals from afocus detection region having a plurality of corresponding displayregions, the image signals being generated by photoelectricallyconverting light having passed through an imaging optical system, and acontrol unit configured to detect a phase difference of the pair ofimage signals output from the focus detection region, and to control aposition of the focus lens based on the phase difference detectionresult, wherein the control unit detects the phase differencecorresponding to divided regions formed by dividing the focus detectionregion, and displays an in-focus state in the display region inaccordance with the control of the focus lens position based on thephase difference detection result corresponding to the divided regions.

Further features and aspects of the present invention will becomeapparent from the following detailed description of exemplaryembodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate exemplary embodiments, features,and aspects of the invention and, together with the description, serveto explain the principles of the invention.

FIG. 1 is a block diagram illustrating a camera configuration accordingto an exemplary embodiment of the present invention.

FIG. 2 is a diagram illustrating a detailed configuration of an opticalsystem for focus detection through a phase difference detection method.

FIG. 3 is a diagram illustrating an arrangement of line sensorsaccording to an exemplary embodiment of the present invention.

FIGS. 4A, 4B, and 4C are diagrams illustrating a positional relationshipbetween AF frames and line sensor fields of view (FOVs) according to afirst exemplary embodiment.

FIG. 5 is a flowchart illustrating an AF operation according to thefirst exemplary embodiment.

FIG. 6 is a diagram illustrating an arrangement of AF frames and linesensors according to a second exemplary embodiment.

FIG. 7 is a flowchart illustrating an AF operation according to thesecond exemplary embodiment.

FIG. 8 is a diagram illustrating an arrangement of AF frames and linesensors according to a third exemplary embodiment.

FIG. 9 is a flowchart illustrating an AF operation according to thethird exemplary embodiment.

FIG. 10 is a flowchart illustrating an AF operation according to afourth exemplary embodiment.

FIGS. 11A and 11B are diagrams illustrating an arrangement and structureof imaging pixels according to a fifth exemplary embodiment.

FIGS. 12A and 12B are diagrams illustrating an arrangement and structureof focus detection pixels for performing pupil division in a horizontaldirection according to the fifth exemplary embodiment.

FIGS. 13A and 13B are diagrams illustrating an arrangement and structureof focus detection pixels for performing pupil division in a verticaldirection according to the fifth exemplary embodiment.

FIG. 14 is a diagram illustrating an arrangement rule of imaging pixelsand focus detection pixels according to the fifth exemplary embodiment.

FIG. 15 is a diagram illustrating an arrangement of AF frames and focusdetection regions according to the fifth exemplary embodiment.

DESCRIPTION OF THE EMBODIMENTS

Various exemplary embodiments, features, and aspects of the inventionwill be described in detail below with reference to the drawings.

FIG. 1 illustrates an example of a camera, as one embodiment of thepresent invention. In FIG. 1, a light flux having passed through animaging optical system including a photographic lens 101 forms anoptical image of an object on an image sensor 108. The photographic lens101 includes a focus lens; the focus lens is used to perform focusadjustment by moving it in an optical axis direction. The image sensor108 is a charge coupled device (CCD) sensor or complementarymetal-oxide-semiconductor (CMOS) sensor, and outputs an image signalobtained by converting the optical image of the object into an electriccharge according to a light quantity of the formed optical imageincident on the sensor.

A main mirror 102 having a semi-transparent area is retracted to theoutside of the imaging light flux when capturing an image, and isobliquely placed within an imaging optical path when detecting a focusstate of an intended target object. In FIG. 1, a state where the mirroris inserted into the imaging light flux (mirror down) is illustrated.The main mirror 102 guides, while being obliquely placed within theimaging optical path, a part of the light flux having passed through theimaging optical system to a finder optical system that includes an AFframe display device 103, a pentaprism 104, and an eyepiece lens 105,and to an AE sensor 106 arranged on top of the eyepiece lens 105. The AFframe display device 103 is a transparent type liquid crystal, andallows a photographer to confirm an AF frame on an imaging screenthrough a finder by displaying the AF frame. The AE sensor 106 is anarea sensor including multiple pixels for capturing an object image fora luminance value of the imaging screen or the object recognition. Atpixel portion, primary color filters of R (red), G (green), and B (blue)are provided. Accordingly, RGB signals of the object image can beoutput.

A sub-mirror 107 is foldable, expandable with respect to the main mirror102 in synchronization with an operation of the main mirror 102. A partof the light flux having passed through the semi-transparent area of themain mirror 102 is reflected downward by the sub-mirror 107, and isincident on an AF sensor 109 and photoelectrically converted intoelectric signals, and a pair of image signals is thus generated.

The detailed configuration of an optical system for focus detection bythe phase difference detection method will now be described withreference to FIG. 2. The light once reflected by the sub-mirror 107forms an image in the vicinity of a FOV mask 206 located on a planeconjugate to an imaging plane. In FIG. 2, an optical path reflected andturned down by the sub-mirror 107 is illustrated in a developing manner.The FOV mask 206 is a member for blocking unwanted light other than afocus detection region (AF frame) within the frame. A field lens 207 hasa function to form an image of respective aperture openings of adiaphragm 208 in the neighborhood of an exit pupil of the photographiclens 101. A secondary imaging lens 209 is arranged on the rear side ofthe diaphragm 208, and respective lenses correspond to respectiveaperture openings of the diaphragm 208. Respective light fluxes havingpassed through the FOV mask 206, the field lens 207, the diaphragm 208,and the secondary imaging lens 209 form images on the line sensors on anAF sensor 109.

Further, the AF sensor 109 is configured so that the light fluxes fromdifferent objects within the imaging scene can form images. The AFsensor 109 detects relative positional shift amount in a divisiondirection of the light flux (from an object) having passed through theimaging optical system, based on the above-described pair of generatedimage signals. Turning back to FIG. 1, a system controller 113 controlsa position of the focus lens to an in-focus position detected based onan output of the AF sensor 109.

The system controller 113 including a central processing unit (CPU) thatperforms control of the entire camera, and a random access memory (RAM)serving as a storage device controls, as appropriate, operations ofrespective components described below. A lens driving device 119 isconnected to the system controller 113, and is provided with acommunication circuit (represented by a bidirectional arrow) thatperforms communication with the photographic lens 101, a lens drivingmechanism that performs lens driving to perform focus adjustment, and adriving circuit thereof. An AF frame display circuit 118 is connected tothe system controller 113, and controls the AF frame display device 103to display the AF frames. A mirror driving circuit 117 is connected tothe system controller 113, and drives the main mirror 102 to and away(outside) the imaging light flux. An AF sensor control circuit 116 isconnected to the system controller 113, and controls the AF sensor 109.An image sensor driving circuit 115 is connected to the systemcontroller 113, and drives the image sensor 108. An AE sensor controlcircuit 114 is connected to the system controller 113, and drives an AEsensor 106. The AE sensor control circuit 114 calculates a luminancevalue of an object, based on RGB signals of the object image output fromthe AE sensor 106, and detects a particular region (e.g., a face) of thetarget object based on luminance distribution information and/or colorinformation.

An image signal determined according to a light quantity of an objectoptical image formed on the image sensor 108 is input into an analogsignal processing circuit 110, and is converted from an analog signal toa digital signal by an analog-to-digital (A/D) converter 111. A digitalsignal processing circuit 112 is connected to the system controller 113,and performs image processing such as shading correction or gammacorrection on the A/D converted signal.

A buffer memory 120 is connected to the digital signal processingcircuit 112, and is a frame memory that can store data for a pluralityof frames captured by the image sensor 108. The A/D converted signalsare temporarily stored in the buffer memory 120. In the digital signalprocessing circuit 112, each processing described above is performedafter reading the data stored in the buffer memory 120, and theprocessed data is again stored in the buffer memory 120.

A recording/reproducing signal processing circuit 121 is connected tothe digital signal processing circuit 112, records the image data in anexternal storage medium 122 such as a memory card, after temporarilystoring image data, in the buffer memory 120, having subjected tovarious types of processing by the digital signal processing circuit112. When the image data is recorded in the external storage medium 122,the recording/reproducing signal processing circuit 121 performscompression of the image data, for example, data compression by jointphotographic experts group (JPEG) process. On the other hand, whenreading the image data from the external storage medium 122, therecording/reproducing signal processing circuit 121 performsdecompression processing of the image data. In the recording/reproducingsignal processing circuit 121, an interface for performing datacommunication with the external storage medium 122 is also included.

A display device 124 displays captured images. There are two patternsfor displaying the images captured by the image sensor 108 on thedisplay device 124. One is a display pattern called a live view forsequentially updating and displaying the images repetitively captured bythe image sensor 108, while the main mirror 102 is moved to the outsideof the imaging light flux. Another is a display pattern called a freezeframe for displaying an image captured by the image sensor 108 for apredetermined time, after release operation of the camera. Further, thedisplay device 124 is also used when image data recorded previously inthe external storage medium 122 is again reproduced and displayed. In acase where an image is displayed on the display device 124, the imagedata stored previously in the buffer memory 120 is read out, and adigital-to-analog (D/A) converter 123 converts the digital image datainto analog video signals. Then, images are displayed on the displaydevice 124 using the analog video signals.

An operation unit 125 is connected to the system controller 113, and isprovided with operation members for operating the camera including apower switch for turning power of the camera on and off, a releasebutton, and a setting button for selecting an image capturing mode suchas human image capturing mode. When these switches and buttons areoperated, a signal corresponding to the operation is input into thesystem controller 113. With the release button, a SW1 which is turned onby a first stroke operation (half-press operation) of the release buttonoperated by a photographer, and a SW2 which is turned on by a secondstroke operation (full-press operation) of the release button, areincluded.

The line sensors (signal generation section) on the AF sensor 109 withinthe imaging screen will be described referring to FIG. 3 and FIG. 4.FIG. 3 is an arrangement diagram of a plurality of line sensors providedon the AF sensor 109, and illustrates a state where the AF sensor 109 isviewed from the front. The present invention can be applied to an AFsensor provided with one or more line sensors each having a plurality ofcorresponding AF frames. Each line sensor is composed of a plurality ofpixels. For example, a line sensor 204 a and a line sensor 204 b of FIG.3 receive light from substantially the same regions of the object by thesecondary imaging lens 209, and are in an optically paired relationship.

FIGS. 4A and 4B are diagrams illustrating reverse projection of the linesensors in FIG. 3 into a finder field of view (FOV) 200, and illustratespositional relationship between the AF frames and the line sensor fieldsof view (FOVs). FIG. 4A illustrates lateral line sensor FOVs, and FIG.4B illustrates longitudinal line sensor fields of view. A line sensorFOV 203 in FIG. 4A corresponds to the line sensor 204 a and the linesensor 204 b in FIG. 3. The AF sensor 109 is provided with a pluralityof line sensors, and at a position corresponding to the line sensor FOV203 among them two AF frames (an AF frame 201 and AF frame 202) arearranged. An enlarged diagram thereof is illustrated in FIG. 4C. An AFframe is equivalent to a display region according to the presentinvention.

In a first exemplary embodiment, descriptions will be given based on thepremise that a focus detection result based on signals obtained by theline sensor 204 a and the line sensor 204 b of FIG. 3 has the bestreliability level as compared with other line sensors, and focusadjustment control is performed based on signals output from the linesensor 204 a and the line sensor 204 b. In the descriptions hereinbelow,the line sensor 204 a and the line sensor 204 b are referred to as linesensors corresponding to the line sensor field of view (FOV) 203.

The focus adjustment operation in the camera according to the firstexemplary embodiment will be described with reference to a flowchart inFIG. 5. In step S101, the system controller 113 determines whether theSW1 is turned ON. If the SW1 is not turned on (NO in step S101), theprocessing is repeated until the SW1 is turned ON. On the other hand, ifthe SW1 is turned on (YES in step S101), the processing proceeds to stepS102.

In step S102, the system controller 113 controls the AF sensor 109 viathe AF sensor control circuit 116 to acquire a pair of image signalsfrom accumulated electric charges. Then, the system controller 113performs focus detection through correlation calculation (phasedifference calculation), which is a publicly known technique, based on apair of image signals obtained from each of a plurality of line sensorpairs. In this case, the calculation is performed using a region 1(whole area) of respective line sensors. For example, a case ofcalculating in the whole area of the line sensor 204 a and the linesensor 204 b of FIG. 3 corresponds to the calculation of the region 1.In this way, by taking relatively a wide region as a calculation rangein a stage of in-focus determination, focus detection can be performedeven when the focusing state of the photographic lens 101 issignificantly defocused. Further, an acquisition ratio of objectcontrast is increased, and as a result, the reliability level of thedetection result can be enhanced.

In step S103, the system controller 113 calculates a reliability foreach detection result of a plurality of line sensor pairs obtained instep S102, and determines and selects one with the highest reliability.As an evaluation value of reliability, an S level (Select Level) valueor the like discussed in, for example, Japanese Patent ApplicationLaid-Open NO. 2007-052072 may be used. Herein, based on the premise thata detection result of the line sensors corresponding to the line sensorFOV 203 is selected by the reliability level determination, a displaymethod for AF frame will be described below.

In step S104, the system controller 113 determines whether the focusingstate is in-focus from a detection result def1 of the line sensorscorresponding to the line sensor FOV 203 selected in step S103. If thedetection result def1 is within a range of in-focus determination value,for example, not larger than ¼Fδ (F: aperture value of lens, δ:permissible circle-of-confusion diameter, for example, for δ=20 μm, 10μm in full-aperture opening of F2.0 lens), the system controller 113determines that the focusing state is in-focus (YES in step S104), andthe processing proceeds to step S106. On the other hand, if thedetection result def1 is larger than the in-focus determination value(for example, ¼Fδ) (NO in step S104), the processing proceeds to stepS105.

In step S105, the system controller 113 converts the detection resultdef1 into a number of pulses, which is a driving amount of the lens, anddrives the photographic lens 101 via the lens driving device 119, andthe processing returns to step S101. Until it is determined that thefocusing state is in-focus in step S104, operations in steps S101 toS105 are repeated.

In this process, the AF frames corresponding to the line sensor FOV 203are two of the AF frame 201 and the AF frame 202. Although both the AFframe 201 and the AF frame 202 may be displayed, the user's intendedobject may be included in only the one AF frame depending on a status ofthe object. In such a case, when both of the AF frames are displayed,the user cannot determine whether focus is achieved on the AF frame inwhich the intended object is included, or focus is achieved on the otherAF frame. Thus, in a case where a focus detection result correspondingto one AF frame contributes more strongly than the other AF frame to thefocus detection result of the entire region 1, control is performed todisplay only the AF frame which contributes more strongly.

In step S106, the system controller 113 performs focus detection bydividing the region 1 in order to perform the display determination forthe AF frame 201 and the AF frame 202 corresponding to the line sensorFOV 203. FIG. 6 illustrates regions of the line sensor FOV 203 for thedisplay determination. In step S106, the system controller 113 performsphase difference calculation on each of the divided regions, usingelectric charge accumulation result (photoelectric conversion result)performed in step S102. The detection result calculated on a region 2 asone of the divided regions (right half of the line sensor FOV 203) isdefined as def2. Further, the detection result calculated on a region 3as another divided region (left half of the line sensor FOV 203) isdefined as def3. The region 2 and the region 3 correspond to a firstdivided region and a second divided region, respectively. In this case,the detection result def2 corresponds to an object of the AF frame 201,and the focus detection result def3 corresponds to an object of the AFframe 202.

The operations performed in the following steps S107 to S109 are relatedto a display determination operation. In step S107, the systemcontroller 113 determines whether a difference between the detectionresult deft of step S106 and the detection result def1 before thedivision of step S102 is smaller than a determination value “a” (firstpredetermined value). If the difference (|def2−def1|) is smaller thanthe predetermined determination value “a” (YES in step S107), theprocessing proceeds to step S108. On the other hand, if the difference(|def2−def1|) is not smaller than the determination value “a” (notsmaller than the first predetermined value) (NO in step S107), theprocessing proceeds to step S109. In this process, the determinationvalue “a” is set to a larger value (for example, 4Fδ) than the in-focusdetermination value. Accordingly, in a case where a detection errorcaused by narrowing the calculation region can be permitted, and onlythe detection result of one region is far apart from the detectionresult of the region 1, the number of displays of the AF frames can bedecreased.

In step S107, the system controller 113 may determine whether |def2| inplace of |def2−def1| is smaller than a determination value “a′”. Thedetermination value “a′” in this case is set to a larger value than thein-focus determination value.

In step S108, the system controller 113 determines a difference betweenthe detection result def3 in step S106 and the detection result def1 instep S102. If the difference (|def3−def1|) is smaller than thedetermination value “a” (YES in step S108), the processing proceeds tostep S111. On the other hand, if the difference (|def3−def1|) is notsmaller than the determination value “a” (not smaller than the firstpredetermined value) (NO in step S108), the processing proceeds to stepS110.

In step S111, the system controller 113 displays both of the AF frame201 and the AF frame 202 via the AF frame display circuit 118 in the AFframe display device 103. This is because the detection result deft anddetection result def3 substantially coincide with the detection resultdeft, based on the display determinations in steps S107 and S108,thereby it is determined that the main object exists both in the AFframe 201 and the AF frame 202.

In step S110, the system controller 113 displays the AF frame 201 in theAF frame display device 103 via the AF frame display circuit 118. Thisis because only the detection result def3 is significantly differentfrom the detection result deft, based on the display determinations insteps S107 and S108, and the detection result of the AF frame 202 isdetermined to be a result corresponding to the background or the likewhich departs from the main object, and it is determined that the mainobject exists in the AF frame 201.

On the other hand, when the processing proceeds to step S109, the systemcontroller 113 also determines a difference between the detection resultdef3 in step S106 and the detection result def1 in step S102. If adifference (|def3−def1|) is smaller than the determination value “a”(YES in step S109), the processing proceeds to step S112. On the otherhand, if the difference (|def3−def1|) is not smaller than thedetermination value “a” (NO in step S109), the processing proceeds tostep S111, and both of the AF frame 201 and the AF frame 202 aredisplayed. This is because it cannot be determined whether the mainobject exists either in the AF frame 201 or in the AF frame 202, sincethe detection result def2 and the detection result def3 are bothsignificantly different from the detection result def1.

In steps S108 and S109, it may be determined whether |def3| in place of|def3−def1| is smaller than the determination value “a′”.

In step S112, the system controller 113 displays the AF frame 202 in theAF frame display device 103 via the AF frame display circuit 118. Thisis because since only the detection result def2 is significantlydifferent from the detection result def1 through the displaydeterminations in steps S107 to S109, the detection result of the AFframe 201 is obtained from the background or the like departing from themain object, and it is determined that the main object exists in the AFframe 202.

In step S113, the system controller 113 determines whether the SW2,which is one of the operation unit 125, is turned ON. If the SW2 is notturned ON (NO in step S113), the operation in step S113 is repeated. Onthe other hand, if the SW2 is turned on (YES in step S113), theprocessing proceeds to step S114.

In step S114, the system controller 113 drives the main mirror 102 tothe outside of the imaging light flux via the mirror driving circuit117, and drives the image sensor 108 to capture an image via the imagesensor driving circuit 115.

After having performed focus detection with respect to the dividedregions in step S106, the system controller 113 may perform calculationof reliabilities similarly to that in step S103 with respect torespective focus detection results before display determinationoperation. If both reliabilities of the region 2 and the region 3 arelarger than the predetermined threshold value, as a result of havingcalculated the reliabilities, the processing proceeds to displaydetermination operation in step S107. On the other hand, if at least oneof reliabilities of the region 2 and the region 3 is not larger than thethreshold value, the processing proceeds to step S111, and the systemcontroller 113 displays both the AF frame 201 and the AF frame 202. Byperforming a display determination operation in a case where thereliabilities of focus detection results for both of the divided regionsare thus high, an erroneous determination due to a detection error canbe prevented.

As described above, in the present exemplary embodiment, by performingcalculation of the region 2 and the region 3 narrower than the region 1(whole area of the line sensor FOV 203), at the time of focus detectionfor display determination (step S106), it can be determined whether themain object exists in an AF frame corresponding to either the region 2or the region 3. At that time, by using a larger value than the in-focusdetermination value as a determination value of the AF frame display,appropriate AF frame display can be performed, while enhancing in-focusaccuracy.

In the present exemplary embodiment, calculation results of the region 2and the region 3 are not used for in-focus control of the focus lens,but are used only for determination of the AF frame display. This isbecause there is a high possibility that an object cannot be captured inthe region 2 or the region 3, or edges cannot be obtained, since theline sensors and the AF frames are arranged with high density. Further,release time lag can be lessened by not using calculation results of theregion 2 and the region 3 for in-focus control of the focus lens.

Furthermore, in the present exemplary embodiment, the number ofcalculations can be decreased, by performing correlation calculation fordisplay determination after performing in-focus detection. This isbecause correlation calculation can be performed based on a detectionresult def1, which has been already determined as within in-focus range,when correlation calculation for display determination is performed(step S106). The increase in release time lag can be restrained, bydecreasing the number of calculations.

In the first exemplary embodiment, the correlation calculation isperformed again on narrow regions (the region 2 and the region 3)corresponding to the AF frames, after in-focus in order to performdisplay determination. In a second exemplary embodiment, contrast valuesin narrow regions (the region 2 and the region 3) corresponding to theAF frames are used at the time of display determination. Theconfiguration of the camera and arrangement of the line sensors aresimilar to those of the first exemplary embodiment, and thereforedescriptions thereof will not be repeated.

A focus adjustment operation in a camera according to the presentexemplary embodiment will be described with reference to a flowchart inFIG. 7. In step S201, the system controller 113 determines whether theSW1 is turned ON. If the SW1 is not turned on (NO in step S201), theprocessing is repeated until the SW1 becomes turned on. On the otherhand, if the SW1 is turned on (YES in step S201), the processingproceeds to step S202.

In step S202, the system controller 113 controls the AF sensor 109 viathe AF sensor control circuit 116, and acquires a pair of image signals.Then, the system controller 113 performs focus detection throughcorrelation calculation, which is a publicly known technique, based on apair of image signals obtained from each of a plurality of line sensorpairs. In this process, calculation is performed on the region 1 (wholearea) of respective line sensors. For example, a case where calculationis performed on a whole area of the line sensor 204 a and the linesensor 204 b in FIG. 3 corresponds to the calculation on the region 1.In this way, by taking relatively wide region as a calculation range ina stage of in-focus determination, focus detection can be performed evenwhen the focusing state of the photographic lens 101 is significantlydefocused. Further, a capturing ratio of an object contrast isincreased, and as a result, the reliability level of the detectionresult can be enhanced.

In step S203, the system controller 113 calculates a reliability foreach of the detection results of the plurality of pairs of line sensorsobtained in step S202, and determines and selects one with the highestreliability. In this case, a display method for AF frame will bedescribed below, based on the premise that a detection result of theline sensors corresponding to the line sensor FOV 203 is selected by thereliability level determination.

In step S204, the system controller 113 determines whether the focusingstate is in-focus from a detection result def1 of the line sensorscorresponding to the line sensor FOV 203 selected in step S203. If thedetection result def1 is within a range of in-focus determination value,for example, not larger than ¼Fδ, the system controller 113 determinesthat the focusing state is in-focus (YES in step S204), and theprocessing proceeds to step S206. On the other hand, if the detectionresult def1 is greater than the in-focus determination value (forexample, ¼Fδ) (NO in step S204), the processing proceeds to step S205.

In step S205, the system controller 113 converts the detection resultdef1 into the number of pulses, which is a driving amount of the lens,and drives the photographic lens 101 via the lens driving device 119,and the processing returns to step S201. Until it is determined that thefocusing state is in-focus in step S204, operations in steps S201 toS205 are repeated.

In step S206, the system controller 113 performs contrast calculation bydividing the region 1 to perform display determination of the AF frame201 and the AF frame 202 corresponding to the line sensor FOV 203. Thatis, the system controller 113 calculates the contrast of the region 2and the contrast of the region 3 of FIG. 6. In this process, the systemcontroller 113 calculates contrast values as contrast calculation byintegrating differences of adjacent pixel signals. The region 2 and theregion 3 correspond to a first display region and a second displayregion, respectively. The contrast value of the region 1 correspondingto the AF frame 201 is defined as cnt1, and the contrast value of theregion 2 corresponding to the AF frame 202 is defined as cnt2.

The operations performed in the following steps S207 to S209 are relatedto a display determination operation. In step S207, the systemcontroller 113 compares the contrast values cnt1 and cnt2 calculated instep S206. If cnt1 is larger than cnt2 (YES in step S207), theprocessing proceeds to step S208. If cnt1 is not larger than cnt2 (NO instep S207), the processing proceeds to step S209.

In step S208, the system controller 113 determines whether the ratio ofthe contrast values cnt1 to cnt2 (ratio of contrasts) calculated in stepS206 is larger than a predetermined value. If the ratio of cnt1/cnt2 islarger than the predetermined determination value “b” (larger than apredetermined ratio) (YES in step S208), the processing proceeds to stepS210. On the other hand, if the ratio of cnt1/cnt2 is not larger thanthe determination value “b” (not larger than the predetermined ratio)(NO in step S208), the processing proceeds to step S211.

In step S209, the system controller 113 determines whether the ratio ofthe contrast values cnt2 to cnt1 calculated in step S206 is larger thanthe predetermined value. If the ration of cnt2/cnt1 is larger than thepredetermined determination value “b” (larger than the predeterminedratio) (YES in step S209), the processing proceeds to step S211. On theother hand, if a ratio of cnt2/cnt1 is not larger than the determinationvalue “b” (not larger than the predetermined ratio) (NO in step S209),the processing proceeds to step S212.

In step S210, the system controller 113 displays the AF frame 201 in theAF frame display device 103 via the AF frame display circuit 118. Thisis because it is determined that the main object exists in the AF frame201, since cnt1 is sufficiently larger than cnt2 through displaydeterminations in steps S207 to S208.

In step S211, the system controller 113 displays the AF frame 202 in theAF frame display device 103 via the AF frame display circuit 118. Thisis because it is determined that the main object exists in the AF frame202, since cnt2 is sufficiently larger than cnt1 through displaydeterminations in steps S207 to S209.

In step S212, the system controller 113 displays both of the AF frame201 and the AF frame 202 via the AF frame display circuit 118 in the AFframe display device 103. This is the processing in a case where it isdetermined that the main object exists in both the AF frame 201 and theAF frame 202, as cnt1 and cnt2 are nearly equal to each other, throughthe display determinations in steps S207 to S209.

In step S213, the system controller 113 determines whether the SW2 asone of the operation unit is turned on. If the SW2 is not turned on (NOin step S213), the processing in step S213 is repeated. On the otherhand, if the SW2 is turned on (YES in step S213), the processingproceeds to step S214.

In step S214, the system controller 113 drives the main mirror 102 tothe outside of the imaging light flux via the mirror driving circuit117, and drives the image sensor 108 to capture an image via the imagesensor driving circuit 115.

As described above, in the present exemplary embodiment, contrast valuesof the region 2 and the region 3 corresponding to the AF frames arecalculated at the time of the display determination, and a position ofthe main object is determined based on the contrast ratio. Generally,since the contrast calculation has less calculation amount than thecorrelation calculation, increase in release time lag can be furtherreduced.

In a third exemplary embodiment, an apparatus that performs displaydetermination different from the first exemplary embodiment and thesecond exemplary embodiment will be described. The configuration of thecamera is similar to that of the first exemplary embodiment, andtherefore descriptions thereof will not be repeated.

FIG. 8 is a diagram illustrating an arrangement of AF range-findingframes and line sensor fields of view (FOVs) within the imaging screenin the present exemplary embodiment. The AF sensor 109 is provided witha plurality of line sensors in two directions perpendicular to eachother, and two AF frames (an AF frame 301 and an AF frame 302)corresponding to a line sensor FOV 303 in a horizontal direction.Further, line sensor FOVs 304 and 305 are arranged in a verticaldirection. The line sensor corresponding to the line sensor FOV 303corresponds to a first focus detection region. Further, the line sensorcorresponding to the line sensor FOVs 304 and 305 corresponds to asecond focus detection region.

In the present exemplary embodiment, a description will be given basedon the premise that focus detection result based on signals obtained bythe line sensors corresponding to the line sensor FOV 303 of FIG. 8 hasthe best reliability level as compared with other line sensors, andfocus adjustment control is performed using the line sensorcorresponding to the line sensor FOV 303.

A focus adjustment operation in a camera according to the presentexemplary embodiment will be described with reference to a flowchart inFIG. 9.

In step S301, the system controller 113 determines whether the SW1 asone of the operation unit is turned ON. If the SW1 is not turned on (NOin step S301), the processing is repeated until the SW1 becomes turnedon. On the other hand, if the SW1 is turned on (YES in step S301), theprocessing proceeds to step S302.

In step S302, the system controller 113 controls the AF sensor 109 viathe AF sensor control circuit 116, and acquires a pair of image signals.Then, the system controller 113 performs focus detection throughcorrelation calculation (phase difference calculation), which is apublicly known technique, based on a pair of image signals obtained fromeach of a plurality of line sensor pairs.

In step S303, the system controller 113 calculates a reliability foreach detection result of a plurality of line sensor pairs obtained instep S302, and determines and selects one with the highest reliability.In this process, a display method for the AF frames will be describedbelow, based on the premise that the detection result of the linesensors corresponding to the line sensor FOV 303 is to be selected,through the reliability level determination.

In step S304, the system controller 113 determines whether the focusingstate is in-focus from a detection result def4 of the line sensorscorresponding to the line sensor FOV 303 selected in step S303. If thedetection result def4 is within a range of an in-focus determinationvalue, for example, not larger than ¼Fδ (F: aperture value of lens, δ:permissible circle-of-confusion diameter, for example, for δ=20 μm, 10μm in full-aperture opening of F2.0 lens), the system controller 113determines that the focusing state is in-focus (YES in step S304), theprocessing proceeds to step S306. On the other hand, if the detectionresult def4 is larger than the in-focus determination value (forexample, ¼Fδ) (NO in step S304), the processing proceeds to step S305.

In step S305, the system controller 113 converts the detection resultdef4 into the number of pulses, which is a driving amount of lens, anddrives the photographic lens 101 via the lens driving device 119, thenthe processing returns to steps S301. The operations in steps S301 toS305 are repeated until it is determined to be in-focus in step S304.

The operations in the following steps S306 to S308 are related to adisplay determination operation. In step S306, it is determined whethera difference between the detection result def4 of the line sensor 303and the detection result def5 of the line sensor 304 calculated in stepS302 is smaller than a predetermined value. If the difference(|def5−def4|) is smaller than a determination value “c” (YES in stepS306), the processing proceeds to step S307. On the other hand, if thedifference (|def5−def4|) is not smaller than the determination value “c”(NO in step S306), the processing proceeds to step S308. In thisprocess, the predetermined value “c” is set to a larger value (forexample, 4Fδ) than an in-focus determination value.

In step S306, it may be determined whether |def5| in place of|def5−def4| is smaller than a determination value “c′”. Thedetermination value “c′” in this case is set to a larger value than thein-focus determination value.

In step S307, it is determined whether a difference between thedetection result def4 of the line sensor FOV 303 in step S302 and adetection result def6 of the line sensor FOV 305 is smaller than thedetermination value “c” (second predetermined value). If the difference(|def6−def4|) is smaller than the determination value “c” (YES in stepS307), the processing proceeds to step S310. On the other hand, if thedifference (|def6−def4|) is not smaller than the determination value “c”(NO in step S307), the processing proceeds to step S309. In step S310,the system controller 113 displays both of the AF frame 301 and the AFframe 302 in the AF frame display device 103 via the AF frame displaycircuit 118. This is because it is determined that the main objectexists in both of the AF frame 301 and the AF frame 302, since thedetection result def5 and the detection result def6 substantiallycoincide with the detection result def4 through display determinationsin steps S306 and S307.

In step S309, the system controller 113 displays the AF frame 301 in theAF frame display device 103 via the AF frame display circuit 118. Thisis because it is determined that the detection result of the AF frame302 is obtained from the background or the like departing from the mainobject, and the main object exists in the AF frame 301, since only thedetection result def6 is significantly different from the detectionresult def4, through the display determinations in steps S306 and S307.

On the other hand, even when the processing proceeds to step S308, thesystem controller 113 determines whether a difference between thedetection result def4 of the line sensor FOV 303 and the detectionresult def6 of the line sensor FOV 305 is smaller than the determinationvalue “c”. If the difference (|def6−def4|) is smaller than thedetermination value “c” (YES in step S308), the processing proceeds tostep S311. On the other hand, if the difference (|def6−def4|) is notsmaller than the determination value “c” (NO in step S308), theprocessing proceeds to step S310. The system controller 113 displaysboth of the AF frame 301 and the AF frame 302. This is because it cannotbe determined whether the main object exists in either the AF frame 301or the AF frame 302, since both of the detection result def5 and thedetection result def6 are significantly different from the detectionresult def4.

In steps S307 and S308, it may be determined whether |def6| in place of(|def6−def4| is smaller than the determination value “c′”.

In step S311, the system controller 113 displays the AF frame 302 in theAF frame display device 103 via the AF frame display circuit 118. Thisis because it is determined that the result of the AF frame 301 isobtained from the background or the like departing from the main object,and the main object exists in the AF frame 302, since only the detectionresult def5 is significantly different from the detection result def4through the display determinations in steps S306 to S308.

In step S312, the system controller 113 determines whether the SW2 asone of the operation unit is turned on. If the SW2 is not turned on (NOin step S312), the processing in step S312 is repeated. On the otherhand, if the SW2 is turned on (YES in step S312), the processingproceeds to step S313.

In step S313, the system controller 113 drives the main mirror 102 tothe outside of the imaging light flux via the mirror driving circuit117, and drives the image sensor 108 to capture an image via the imagesensor driving circuit 115.

As described above, in a case where two AF frames 301 and 302 exist onthe line sensor FOV 303 for performing focus adjustment, the AF frame inwhich the main object exists can be determined from the detectionresults of the line sensor FOVs 304 and 305 perpendicular to the linesensor FOV 303.

In a fourth exemplary embodiment, an apparatus that performs displaydeterminations different from the above-described exemplary embodimentswill be described. The configuration of the camera and arrangement ofthe line sensors are similar to those in the first exemplary embodiment,and therefore descriptions thereof will not be repeated.

In the present exemplary embodiment, descriptions will be given based onthe premise that focus detection result based on signals obtained by theline sensors corresponding to the line sensor FOV 203 of FIG. 3 has thebest reliability level as compared with other line sensors, and focusadjustment control is performed by the line sensors corresponding to theline sensor FOV 203.

A focus adjustment operation in the camera according to the presentexemplary embodiment will be described with reference to a flowchart ofFIG. 10.

In step S401, the system controller 113 determines whether the SW1 asone of the operation unit is turned ON. If the SW1 is not turned on (NOin step S401), the processing is repeated until the SW1 is turned ON. Onthe other hand, if the SW1 is turned on (YES in step S401), theprocessing proceeds to step S402.

In step S402, the system controller 113 controls the AF sensor 109 viathe AF sensor control circuit 116, and acquires a pair of image signals.Then, the system controller 113 performs focus detection throughcorrelation calculation (phase difference calculation), which is apublicly known technique, based on accumulated signals of a plurality ofline sensors.

In step S403, the system controller 113 calculates a reliability foreach detection result of a plurality line sensor pairs obtained in stepS402, and determines and selects one with the highest reliability. Inthis process, a display method for AF frames will be described below,based on the premise that detection result of the line sensorscorresponding to the line sensor FOV 203 is to be selected.

In step S404, the system controller 113 determines whether the focusingstate is in-focus from a detection result def1 of the line sensorscorresponding to the line sensor FOV 203 selected in step S403. If thedetection result def1 is within a range of in-focus determination value,for example, not larger than ¼Fδ (F: aperture value of lens, 6:permissible circle-of-confusion diameter, for example, for δ=20 μm, 10μm in full-aperture opening of F2.0 lens), the system controller 113determines that the focusing state is in-focus (YES in step S404), theprocessing proceeds to step S406. On the other hand, if the detectionresult def1 is larger than the in-focus determination value (forexample, ¼Fδ) (NO in step S404), the processing proceeds to step S405.

In step S405, the system controller 113 converts the detection resultdef1 into the number of pulses, which is a driving amount of the lens,and drives the photographic lens 101 via the lens driving device 119,then the processing returns to step S401. The operations in steps S401to S405 are repeated until it is determined to be in-focus in step S404.

In step S406, the AE sensor control circuit 114 detects a specificobject, based on signals captured by the AE sensor 106. In this process,the AE sensor control circuit 114 performs face detection, which is apublicly known technique as specific object detection, and when a faceis present in the imaging screen, and transmits information such as sizeand position of a face region to the system controller 113.

The operations in the following steps S407 to S409 are related to adisplay determination operation. In step S407, the system controller 113determines whether the face region detected in step S406 is present inthe AF frame 201. If a face or a part of the face is present within theAF frame 201 (YES in step S407), the processing proceeds to step S408.On the other hand, if the face is not present in the AF frame 201 (NO instep S407), the processing proceeds to step S409.

In step S408, the system controller 113 determines whether the faceregion detected in step S406 is present in the AF frame 202. If the faceor a part of the face is present in the AF frame 202 (YES in step S408),the processing proceeds to step S410. On the other hand, if the face isnot present within the AF frame 202 (NO in step S408), the processingproceeds to step S412.

In step S409, the system controller 113 determines whether the faceregion detected in step S406 is present in the AF frame 202. If the faceor a part of the face is present in the AF frame 202 (YES in step S409),the processing proceeds to step S411. On the other hand, if the face isnot present in the AF frame 202 (NO in step S409), the processingproceeds to step S410.

In step S410, the system controller 113 displays both of the AF frame201 and the AF frame 202 in the AF frame display device 103 via the AFframe display circuit 118. The operation is the processing when a faceas the main object is present in both of the AF frame 201 and the AFframe 202, or when a face is not present in both of the AF frame 201 andthe AF frame 202, through the display determinations in steps S407 toS409. In the present exemplary embodiment, since discrimination of themain object cannot be performed when a face is not present in both ofthe AF frames, both of the AF frame 201 and the AF frame 202 aredisplayed.

In step S411, the system controller 113 displays the AF frame 202 in theAF frame display device 103 via the AF frame display circuit 118. Theoperation is the processing when a face as the main object is present inthe AF frame 202, through the display determinations in step S407 toS409.

In step S412, the system controller 113 displays the AF frame 201 in theAF frame display device 103 via the AF frame display circuit 118. Theoperation is the processing when a face as the main object is present inthe AF frame 201, through the display determinations in steps S407 toS409.

In step S413, the system controller 113 determines whether the SW2 asone of the operation unit is turned on. If the SW2 is not turned on (NOin step S413), the processing in step S413 is repeated. On the otherhand, if the SW2 is turned on (YES in step S413), the processingproceeds to step S414.

In step S414, the system controller 113 drives the main mirror 102 tothe outside of the imaging light flux via the mirror driving circuit117, and drives the image sensor 108 to capture an image via the imagesensor driving circuit 115.

As described above, in the present exemplary embodiment, when two AFframes 201 and 202 are present on the line sensor 203, an AF frame wherethe main object exists can be determined, by performing face detectionwithin the imaging scene, and displaying the AF frame 201 and the AFframe 202 corresponding to the face region.

In a fifth exemplary embodiment, an apparatus that performs focusadjustment control by the image sensor 108 at the time of live view,instead of focus adjustment control of the phase difference detectionmethod by the AF sensor 109, will be described.

FIGS. 11A to 13B are diagrams illustrating a structure of an imagingpixel and that of a focus detection pixel. In the fifth exemplaryembodiment, a Bayer array is employed in which two pixels having G(green color) spectral sensitivity are diagonally arranged in 2 rows×2columns=4 pixels, and pixels respectively having R (red color) and B(blue color) spectral sensitivities are arranged as the other twopixels. Then, focus detection pixels with a structure as will bedescribed below are distributed and arranged between pixels of the Bayerarrays in accordance with a predetermined rule.

FIGS. 11A and 11B are diagrams illustrating an arrangement and astructure of imaging pixels. FIG. 11A is a plan view of 2 rows×2 columnsimaging pixels. As is generally known, in the Bayer array, G pixels arediagonally arranged, and R and B pixels are arranged as the other twopixels. This 2 rows×2 columns structure is repetitively arranged.

A cross section taken along a line A-A in FIG. 11A is illustrated inFIG. 11B. ML is an on-chip microlens arranged on the foreground of eachpixel, CF_(R) is a color filter of R (Red), and CF_(G) is a color filterof G (Green), photodiode (PD) is schematic representation ofphotoelectric conversion portion, a contact layer (CL) is a wiring layerfor forming a signal line which transmits various types of signals. TLis schematic representation of an imaging optical system.

The on-chip microlens ML and photoelectric conversion portion PD foreach imaging pixel are configured to capture a light flux which haspassed through the imaging optical system taking lens (TL) aseffectively as possible. In other words, an exit pupil (EP) of theimaging optical system TL and the photoelectric conversion portion PDare in a conjugate relationship due to the microlens ML, and theeffective area of the photoelectric conversion portion is designed tohave large effective area. FIG. 11B illustrates a light flux enteringthe R pixel, but the G pixel and B (Blue) pixel also have the samestructure. Therefore, the exit pupil EP corresponding to each of R, G,and B imaging pixels has a large diameter, and a light flux (lightquantum) from an object can be efficiently captured to increase the S/Nratio of an image signal.

FIGS. 12A and 12B illustrate an arrangement and a structure of focusdetection pixels for performing pupil division in the horizontaldirection (lateral direction) of the imaging optical system. Thehorizontal direction or lateral direction is defined as, when the userholds a camera so that an optical axis of the imaging optical systembecomes parallel to the horizontal direction, a direction along astraight line which is perpendicular to the optical axis, and extends inthe horizontal direction. FIG. 12A is a plan view of pixels of 2 rows×2columns including focus detection pixels. When obtaining an image signalfor recording or viewing, the main component of luminance information isacquired by G pixel. The image recognition characteristics of humans aresensitive to luminance information. Thus, if G pixels are missed,degradation of the image quality is easily perceived. On the other hand,R or B pixels are used to acquire color information (color differenceinformation). However, the visual characteristics of humans are notsensitive to color information. Hence, even when pixels for acquiringcolor information are slightly missed, degradation of image quality ishardly recognized. Thus, in the present exemplary embodiment, G pixelsout of 2 rows×2 columns pixels are left as imaging pixels, and R and Bpixels are replaced with focus detection pixels. In FIG. 12A, S_(HA) andS_(HB) represent focus detection pixels.

A cross section taken along the line A-A in FIG. 12A is illustrated inFIG. 12B. The microlens ML and the photoelectric conversion portion PDhave the same structure as those of the imaging pixels illustrated inFIG. 11B. In the present exemplary embodiment, a signal from the focusdetection pixel is not used for image generation, so that a transparentfilm CF_(W) (white) is arranged in place of a color filter for colorseparation. To perform pupil division by the image sensor 108, theaperture opening of the wiring layer CL deviates in one direction fromthe center line of the microlens ML. More specifically, since it iseccentric to right side, an aperture opening OP_(HA) of the pixel S_(HA)receives a light flux which has passed through an exit pupil EP_(HA) onthe left side of the imaging optical system TL. Similarly, an apertureopening OP_(HB) of the pixel S_(HB) deviates to the left, and receives alight flux having passed through a right exit pupil EP_(HB) of theimaging optical system TL. Therefore, the pixels S_(HA) are arrayedregularly in the horizontal direction, and the object image acquired bythese pixel groups is defined as “A” image. The pixels S_(HB) are alsoarrayed regularly in the horizontal direction, and the object imageacquired by these pixel groups is defined as “B” image. Then, bydetecting the relative positions of the “A” and “B” images, the focusdetection of the object image can be performed.

The above-described pixels S_(HA) and S_(HB) can detect the focus of anobject, for example, a vertical line having a luminance distribution inthe lateral direction of the imaging scene, but cannot detect the focusof a horizontal line having a luminance distribution in the longitudinaldirection. Thus, in the present exemplary embodiment, to enable focusdetection in the horizontal line, there is also provided pixels fordividing the pupil even in the vertical direction (longitudinaldirection) of the imaging optical system.

FIGS. 13A and 13B illustrate the arrangement and structure of the focusdetection pixels for dividing the pupil in the vertical direction (inother words, the top-to-bottom direction or longitudinal direction) ofthe imaging optical system. The vertical direction, top-to-bottomdirection, or longitudinal lateral direction is defined as a directionalong a straight line perpendicular to the optical axis and extends inthe vertical direction when the user holds the camera so that theoptical axis of the imaging optical system becomes parallel to thehorizontal direction. FIG. 13A is a plan view of 2 rows×2 columns pixelsincluding the focus detection pixels. Similar to FIG. 12A, G pixels areleft as imaging pixels, and R and B pixels are replaced with focusdetection pixels. In FIG. 13A, S_(VC) and S_(VD) represent the focusdetection pixels.

A cross section taken along a line A-A of FIG. 13A is illustrated inFIG. 13B. The pixel in FIG. 12B has a structure for separating the pupilin the lateral direction, but the pixels in FIG. 13B only have pupilseparation direction in the longitudinal direction, and have the samestructure of the pixels in FIG. 12B. More specifically, an apertureopening OP_(VC) of the pixel S_(VC) deviates downward, and as a result,receives a light flux having passed through an upper exit pupil EP_(VC)of the imaging optical system TL. Similarly, an aperture opening OP_(VD)of the pixel S_(VD) deviates upward, and as a result, receives a lightflux having passed through a lower exit pupil EP_(VD) of the imagingoptical system TL. Therefore, pixels S_(VC) are arrayed regularly in thevertical direction, and an object image acquired by these pixel groupsis defined as “C” image. Also, pixels S_(VD) are arrayed regularly inthe vertical direction, and an object image acquired by these pixelgroups is defined as “D” image. By detecting relative positions of the“C” image and the “D” image, an out-of-focus amount (defocus amount) ofthe object image having a luminance distribution in the verticaldirection can be detected.

FIG. 14 is a diagram illustrating an arrangement rule for imaging pixelsand focus detection pixels illustrated in FIG. 11A through FIG. 13B.FIG. 14 is a diagram illustrating an arrangement rule for a minimum unitwhen discretely arranging focus detection pixels between the imagingpixels. In FIG. 14, 10 rows×10 columns=100 pixels are defined as oneblock. Then, in upper leftmost block BLK (1, 1), bottom leftmost R pixeland B pixel are replaced with a pair of focus detection pixels S_(HA)and S_(HB) for performing pupil division in the horizontal direction.

In a block BLK (1, 2) on the immediate right side of the BLK (1, 1), thebottom leftmost R pixel and B pixel are similarly replaced with a pairof focus detection pixels S_(VC) and S_(VD) for performing pupildivision in the vertical direction. Further, a block BLK (2, 1) adjacentbelow the first block BLK (1, 1) has the same pixel array as that of theblock BLK (1, 2). Then, a block BLK (2, 2) on the immediate right sideof the BLK (2, 1) has the same pixel array as that of the first blockBLK (1, 1).

When this arrangement rule is universally expressed, in a block BLK (i,j), a focus detection pixel for horizontal pupil division is arrangedwhen (i+j) is an even number, and a focus detection pixel for verticalpupil division is arranged when (i+j) is an add number. The focusdetection pixel arranges are arranged in a whole area of the imagingscreen in this unit. By extracting the focus detection pixels discretelyarranged in this way in the frame whole area by a predetermined regionunit, focus detection can be performed with respect to a plurality ofregions on the imaging frame, like the line sensors of the AF sensor109.

In the present exemplary embodiment, the digital signal processingcircuit 112 is provided with a detection circuit that detects in-focusstate of the photographic lens 101 according to object image signalsoutput from the focus detection pixels of the image sensor 108

FIG. 15 is a diagram illustrating an arrangement of AF frames and focusdetection regions in the imaging screen in the fifth exemplaryembodiment.

On a focus detection region 503, which is one of a plurality of focusdetection regions, in the horizontal direction, two AF frames (an AFframe 501 and an AF frame 502) are arranged. Further, in the AF frame501 and the AF frame 502, a focus detection region 504 and a focusdetection region 505 each are arranged in the vertical direction.

The display determination of the AF frames 501 and 502 enables displayof the AF frames appropriately by applying the display determinationswhich have been described in the above exemplary embodiments. The AFframes which have been display-determined are displayed from the displaydevice 124 by the digital signal processing circuit 112.

As described above, even when an imaging plane phase difference AF isperformed as in the present exemplary embodiment, display determinationof the present invention can be performed.

Embodiments of the present invention can also be realized by a computerof a system or apparatus that reads out and executes computer executableinstructions recorded on a storage medium (e.g., non-transitorycomputer-readable storage medium) to perform the functions of one ormore of the above-described embodiment(s) of the present invention, andby a method performed by the computer of the system or apparatus by, forexample, reading out and executing the computer executable instructionsfrom the storage medium to perform the functions of one or more of theabove-described embodiment(s). The computer may comprise one or more ofa central processing unit (CPU), micro processing unit (MPU), or othercircuitry, and may include a network of separate computers or separatecomputer processors. The computer executable instructions may beprovided to the computer, for example, from a network or the storagemedium. The storage medium may include, for example, one or more of ahard disk, a random-access memory (RAM), a read only memory (ROM), astorage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all modifications, equivalent structures, and functions.

This application claims priority from Japanese Patent Application No.2012-137923 filed Jun. 19, 2012, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A focus adjustment apparatus configured todisplay an in-focus state in a display region in accordance with controlof a focus lens position, the focus adjustment apparatus comprising: asignal generation unit configured to output a pair of image signals froma focus detection region, the image signals being generated byphotoelectrically converting light having passed through an imagingoptical system; and a control unit configured to detect a defocus amountbased on the pair of image signals output from a first focus detectionregion having a plurality of corresponding display regions, and tocontrol a position of the focus lens based on the defocus amountcorresponding to the first focus detection region, wherein the controlunit detects a defocus amount corresponding to each of second focusdetection regions which are arranged in a different detection from thefirst focus detection region, and determines at least one display regionto indicate an in-focus state from among the display regionscorresponding to the first focus detection region, in accordance withthe control of the focus lens position, based on the defocus amountcorresponding to each of the second focus detection regions.
 2. Thefocus adjustment apparatus according to claim 1, wherein the controlunit determines, to indicate an in-focus state, a display regioncorresponding to the second focus detection region of which differencein defocus amount from the first focus detection region is smaller thanthat of another second focus detection region.
 3. The focus adjustmentapparatus according to claim 2, wherein the control unit determines, toindicate an in-focus state, a display region corresponding to the secondfocus detection region of which difference in defocus amount from thefirst focus detection region is smaller than a first predeterminedvalue.
 4. The focus adjustment apparatus according to claim 3, whereinthe control unit determines, if a difference in defocus amount from thefirst focus detection region is not smaller than the first predeterminedvalue in all second focus detection regions, all display regionscorresponding to the first focus detection region to indicate anin-focus state.
 5. The focus adjustment apparatus according to claim 1,wherein the control unit determines, after moving the focus lens to aposition at which the defocus amount of the first focus detection regionbecomes smaller than a predetermined determination value, a displayregion to indicate an in-focus state based on the defocus amountcorresponding to each of the second focus detection regions.
 6. Thefocus adjustment apparatus according to claim 5, wherein the controlunit determines, to indicate an in-focus state, a display regioncorresponding to a second focus detection region of which difference indefocus amount from the first focus detection region is smaller than afirst predetermined value, and wherein the first predetermined value isgreater than the predetermined determination value.
 7. The focusadjustment apparatus according to claim 5, wherein the control unituses, in a case where the defocus amount corresponding to each of thesecond focus detection regions is detected, a photoelectric conversionresult of each of the second focus detection regions when the defocusamount corresponding to the first focus detection region has becomesmaller than the predetermined determination value.
 8. The focusadjustment apparatus according to claim 1, wherein the signal generationunit is provided with a plurality of the first focus detection regions,and generates and outputs the pair of image signals from respectivefirst focus detection regions, and wherein the control unit calculates areliability of the pair of image signals, and controls a position of thefocus lens based on the defocus amount corresponding to the first focusdetection region which has generated an image signal with the highestreliability.
 9. The focus adjustment apparatus according to claim 1,wherein the control unit calculates a reliability of the pair of imagesignals in each of the second focus detection regions, and in a casewhere the reliability is not larger than a predetermined thresholdvalue, displays an in-focus state in all display regions correspondingto the first focus detection region.
 10. The focus adjustment apparatusaccording to claim 1, wherein the second focus detection regions arearranged perpendicular to the first focus detection region.
 11. Acontrol method for a focus adjustment apparatus configured to display anin-focus state in a display region in accordance with control of a focuslens position, the method comprising: outputting a pair of image signalsfrom a focus detection region, the image signals being generated byphotoelectrically converting light having passed through an imagingoptical system; detecting a defocus amount based on the pair of imagesignals output from a first focus detection region having a plurality ofcorresponding display regions; controlling a position of the focus lensbased on the defocus amount corresponding to the first focus detectionregion; detecting a defocus amount corresponding to each of second focusdetection regions which are arranged in a different direction from thefirst focus detection region; and determining at least one displayregion to indicate an in-focus state from among the display regionscorresponding to the first focus detection region in accordance with thecontrol of the focus lens position, based on the defocus amountcorresponding to each of the second focus detection regions.
 12. A focusadjustment apparatus configured to display an in-focus state in adisplay region in accordance with control of a focus lens position, thefocus adjustment apparatus comprising: a signal generation unitconfigured to output a pair of image signals from a focus detectionregion, the image signals being generated by photoelectricallyconverting light having passed through an imaging optical system; and acontrol unit configured to detect a defocus amount based on the pair ofimage signals output from a first focus detection region having aplurality of corresponding display regions, and to control a position ofthe focus lens based on the defocus amount corresponding to the firstfocus detection region, wherein the control unit detects a defocusamount corresponding to each of second focus detection regions which arearranged adjacent to the first focus detection region, and determines atleast one display region to indicate an in-focus state from among thedisplay regions corresponding to the first focus detection region, inaccordance with the control of the focus lens position based on thedefocus amount corresponding to each of the second focus detectionregions.
 13. A control method for a focus adjustment apparatusconfigured to display an in-focus state in a display region inaccordance with control of a focus lens position, the method comprising:outputting a pair of image signals from a focus detection region, theimage signals being generated by photoelectrically converting lighthaving passed through an imaging optical system; detecting a defocusamount based on the pair of image signals output from a first focusdetection region having a plurality of corresponding display regions;controlling a position of the focus lens based on the defocus amountcorresponding to the first focus detection region; detecting a defocusamount corresponding to each of second focus detection regions which arearranged adjacent to the first focus detection region; and determiningat least one display region to indicate an in-focus state from among thedisplay regions corresponding to the first focus detection region, inaccordance with the control of the focus lens position, based on thedefocus amount corresponding to each of the second focus detectionregions.
 14. A focus adjustment apparatus configured to display anin-focus state in a display region in accordance with control of a focuslens position, the focus adjustment apparatus comprising: a signalgeneration unit configured to output a pair of image signals from afocus detection region, the image signals being generated byphotoelectrically converting light having passed through an imagingoptical system; and a control unit configured to detect a defocus amountbased on the pair of image signals output from a first focus detectionregion having a plurality of corresponding display regions, and tocontrol a position of the focus lens based on the defocus amountcorresponding to the first focus detection region, wherein a pluralityof second focus detection regions are arranged across the first focusdetection region, and each of the display regions corresponding to thefirst focus detection region is arranged corresponding to anintersection of the first focus detection region and each of the secondfocus detection regions, wherein the control unit detects a defocusamount corresponding to each of the second focus detection regions, anddetermines at least one display region to indicate an in-focus statefrom among the display regions corresponding to the first focusdetection region based on the defocus amount corresponding to the firstfocus detection region and the defocus amount corresponding to each ofthe second focus detection regions.
 15. A control method for a focusadjustment apparatus configured to display an in-focus state in adisplay region in accordance with control of a focus lens position, themethod comprising: outputting a pair of image signals from a focusdetection region, the image signals being generated by photoelectricallyconverting light having passed through an imaging optical system;detecting a defocus amount based on the pair of image signals outputfrom a first focus detection region having a plurality of correspondingdisplay regions; controlling a position of the focus lens based on thedefocus amount corresponding to the first focus detection region;detecting a defocus amount corresponding to each of a plurality ofsecond focus detection regions, wherein the second focus detectionregions are arranged across the first focus detection region, and eachof the display regions corresponding to the first focus detection regionis arranged corresponding to an intersection of the first focusdetection region and each of the second focus detection regions; anddetermining at least one display region to indicate an in-focus statefrom among the display regions corresponding to the first focusdetection region based on the defocus amount corresponding to the firstfocus detection region and the defocus amount corresponding to each ofthe second focus detection regions.